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Rare-earth metalation of calix[4]pyrrole/calix[4]arene free of alkali-metal companions


Deacon, GB and Gardiner, MG and Junk, PC and Townley, JP and Wang, J, Rare-earth metalation of calix[4]pyrrole/calix[4]arene free of alkali-metal companions, Organometallics, 31, (10) pp. 3857-3864. ISSN 0276-7333 (2012) [Refereed Article]

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Copyright 2012 American Chemical Society

DOI: doi:10.1021/om2011134


The redox transmetalation/protolysis (RTP) reactions of ytterbium or neodymium metal with calix[4]H4 (5,11,17,23-tetra-tert-butylcalix[4]arene-25,26,27,28-tetrol) in the presence of bis(pentafluorophenyl)mercury under ultrasonication yielded [LnIII(calix[4]H)(thf)]2 (1, Ln = Yb; 2, Ln = Nd). The characterization of both 1 and 2, including an X-ray single-crystal structural determination for 2, suggests triple deprotonation of the macrocyclic ligand on metalation. The related RTP reaction of H4N4Et8 (meso-octaethylcalix[4]pyrrole) with ytterbium metal and Hg(C6F5)2 at ambient temperature, however, resulted in quadruple deprotonation and afforded the ytterbium(II) calix[4]pyrrolide complex [Yb2(N4Et8)(thf)4] (3) in good yield. Subsequent oxidation of 3 by dioxygen generated the novel tetranuclear ytterbium(III) complex [Yb4(μ-O)2(N4Et8)2(thf)2] (4). The structures of the ytterbium(II) complex 3 and the ytterbium(III) complex 4 incorporate endo (3) and endo/exo (4) pyrrolide sandwich and half-sandwich units, respectively, with metal centers η1 bound by nitrogen and η5 bonded by pyrrolide rings. The RTP reaction of lanthanum metal using diphenylmercury in place of bis(pentafluorophenyl)mercury gave the triply deprotonated and N-confused pyrrolide (with an alkyl substituent of one pyrrolide ring migrated to a β-position) macrocyclic complex [La2(HN3N'Et8)2] (5). The triple deprotonation of the macrocyclic ligand H4N4Et8 was also achieved through its reaction with 3 molar equiv of potassium metal, giving colorless crystals of [{K3(HN4Et8)(thf)(PhMe)2}n] (6). However, an attempt to isolate the corresponding partially deprotonated calix[4]pyrrolide ytterbium(III) complex through the metathesis reaction of potassium precursor 6 with ytterbium triiodide was unsuccessful.

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Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Inorganic chemistry
Research Field:F-block chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Gardiner, MG (Associate Professor Michael Gardiner)
ID Code:78555
Year Published:2012
Web of Science® Times Cited:17
Deposited By:Chemistry
Deposited On:2012-07-07
Last Modified:2017-10-25

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